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LDO regulator extends battery life

Posted: 09 Aug 2005 ?? ?Print Version ?Bookmark and Share

Keywords:vishay intertechnology? low-dropout regulator? ldo regulator? sip21101? sip21102?

The two new 150mA low-noise low-dropout (LDO) regulators from Vishay Intertechnology Inc. are touted to have the highest available current density in the 5-pin SC-70 package. According to the company, their extremely small 2-by-2mm footprint makes them well-suited for use in battery-powered equipment such as cellphones, PDAs, pagers, digital cameras, MP3 players, cable and DSL modems, and other noise-sensitive electronics.

Under a 150mA load condition, the SiP21101 and SiP21102 feature a low dropout of 130mV and a ground current of 110?A, helping to prolong battery life in low-voltage portable electronic systems. Designed to maintain regulation while delivering 300mA peak current, these new ICs both feature a fast start-up time of 50?s. Fifteen fixed output voltage options ranging from 1.2V to 5V are available.

An active pull-down circuit is built into the devices to clamp the output voltage when it rises beyond normal regulation, discharging it automatically by connecting the output to ground through a 100-ohm n-channel MOSFET when the device is put in shutdown mode. Vishay explained that this provides better transient response and regulation. Reverse battery protection limits the reverse current flow to approximately 1?A to prevent damage to the IC in the event that a reversed battery is applied at the input. Short circuit and thermal protection are also built in.

The SiP21101 provides a quiet voltage source because of an external noise bypass capacitor connected to its BP pin that reduces noise to 30?V. The same pin on the SiP21102, which has a noise output of 75?V, functions as an error flag output that goes low when the output voltage drops 4 percent below its normal voltage.

The company added that both the SiP21101 and SiP21102 use low-cost ceramic capacitors or tantalum capacitors, giving designers a flexible choice of magnetic components.

Samples and production quantities are already available for most voltage options, with lead times of 6 to 8 weeks for larger orders. Pricing is 40 cents each in 1,000-piece quantities.

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